At this point, it might occur to us to ask why Nāgārjuna introduces the distinction
between conventional truth and ultimate truth in the first place, if they are not different,and we might similarly wonder why the Buddha distinguishes nirvana from saṃsāra, if ultimately they are the same. As we shall see, this is due, in part at least, to the limitations of language, that is, to the impossibility of saying anything at all that corresponds precisely to ultimate truth.
Emptiness cannot simply be affirmed because there is no way to express the idea without, at first, setting up a dichotomy between the conventional and the ultimate. Yet, Nāgārjuna warns,
"Empty" should not be asserted.
"Nonempty" should not be asserted.
Neither both nor neither should be asserted.
They are only used nominally (MMK 22:11; Garfield 1995, 61).
The central idea here, according to Garfield, is that all assertion can only be
conventionally true and this includes, of course, all discourse about the ultimate nature of things (1995, 280). From the ultimate perspective, that is, nothing can be said at all, and this is because language itself seems to encourage reification and the belief in svabhāva.
By demarcating individual objects and events in the experiential field, and applying
names to them, it deceives us into believing that those things exist from their own side,independently of our conceptualization. "The very act of referring to an entity", explains Richard King, "necessitates its self-identity"(King 1994, 671). There is a natural tendency, in other words, to believe in the inherent reality of that which we name, and to assume that something ultimately real corresponds to our words, and matches our concepts.
One example of this occurs when the phrase "this is empty" leads us to think of emptiness as something inherently existent. This is why Nāgārjuna claims emptiness
should not be affirmed.
The passage cited above, therefore, draws attention to the tendency of language to impose svabhāva on those aspects of reality carved up through our terms (Streng 1973,32–33).